Apparatus and Methods For Providing Uniformly Volume Distributed Combustion of Fuel

ABSTRACT

A combustor apparatus and method for the combustion of viscous fuels are provided. The combustor apparatus can include a precombustion chamber particularly adapted to heat and at least partially combust a heavy primary fuel, and a main combustion chamber adapted to combust the primary fuel uniformly through the main combustion chamber (in flameless mode). The precombustion chamber can include at least one air injection inlet port positioned to induce a first stage vortex in the main body portion of the housing of the precombustion chamber. Further, the precombustion chamber can be interfaced with a main combustion chamber to induce a second stage vortex within the main combustion chamber. The main combustion chamber can have an extended axial length in order to accommodate heavier fuels that require additional time to sufficiently combust (oxidize) within the combustion chamber.

RELATED APPLICATIONS

This non-provisional application claims priority to and the benefit of U.S. Patent Application No. 61/176,006, filed May 6, 2009, titled “Apparatus and Methods for Providing Uniformly Volume Distributed Combustion of Fuel,” incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fuel combustion processes and apparatus, and specifically to apparatus for providing uniformly volume distributed combustion and related methods.

2. Description of Related Art

It was arguably not until the late 1970s and early 1980s, as a result of the first and the second energy crisis, that research and development activities began to seriously focus on improving energy efficiency. Similarly, it has only been since until after such time period that industry has truly recognized the need for eliminating noxious pollutants such as nitrogen oxides, mostly due to concerns over human health and concern for the environment. As a result, although uniformly distributed (flameless) combustion was discovered circa 1911, it was not until recently that uniformly distributed combustion (flameless oxidation) has become a focus of industrial research.

In flameless combustion, ignition occurs and progresses with generally no visible or audible signs of a flame usually associated with burning. As early as 1989, it was found that combustion in a furnace could be sustained even in an extremely low concentration of oxygen, if the combustion air was sufficiently preheated. Particularly, during experiments with a self-recuperative burner, it was observed that at furnace combustion temperatures of about 1000° C. and an air preheat temperature of about 650° C., no flame was visible and no ultraviolet signal was detected. Nevertheless, the fuel was substantially combusted “burnt,” and the carbon monoxide content and nitric oxide of the exhaust was found to be extremely low.

Conventionally, to initiate flameless combustion, preheated oxidizing air and fuel gas is fed into a combustion chamber at relatively high injection speeds. The geometry of the combustion chamber, as well as the injection speed of the fuel-air mixture, create large internal recirculations of the combustion mixture. Once the recirculations are sufficient, the combustion becomes distributed throughout the volume of the combustion chamber and the flame will no longer be visible. Further, as an application of such principle, nitric oxide emission can be reduced by dilution of the combustion air with recirculated burned gas in the furnace. Dilution of the combustion air can reduce the oxygen content of the oxidizer, which decreases temperature fluctuations in the combustion chamber as well as the mean temperature, hence, a resultantly low amount of nitric oxide emission.

Recognizing the potential benefits of flameless combustion, the industry has attempted to develop various types of combustion chambers that support flameless combustion. For example, U.S. Pat. No. 6,796,789 by Gibson et al. titled Method to Facilitate Flameless Combustion Absent Catalyst or High-Temperature Oxidant” describes and oval-shaped combustion chamber configured to recirculate fuel gas with flue gas and combustible air. U.S. Pat. No. 5,340,020 by Manus et al. Titled “Method and Apparatus for Generating Heat by Flameless Combustion of a Fuel in a Gas Flow” describes a combustion apparatus, which utilizes a catalyst for producing the flameless combustion.

U.S. Pat. No. 5,839,270 by Jirnov et al., titled “Sliding-Blade Rotary Air-Heat Engine with Isothermal Compression of Air” describes a particularly effective combustion chamber originally configured for use with the sliding-blade rotary air-heat engine. The Jirnov “vortex” combustion combined with a straight-flow precombustion chamber successfully solved problems associated with operating on multi-fuels with a high completeness of combustion over the wide range of the coefficient of air redundance, while producing a substantial drop in toxicity of the exhaust gases. The combustor was also characterized by providing a simplified combustor design and ease of fabricating, high thermal and volumetric efficiency, while being able to employ a variety of types of combustible hydrocarbon gas or liquid fuels. The vortex combustor provided a vortex chamber positioned at the tube inlet and ejectors with feedback loops positioned along the length of the heat transfer section. This enabled the results to he increased by inducing a swirl flow and intensive recirculation of fluid all along the length of the heat transfer section. A precombustion chamber was provided to form a super-rich fuel and air mixture, ignition, partial combustion and pyrolyzation of heavy and low grade fuels. In operation with the Jirnov engine, prior to entering the precombustion chamber the combustion air was first preheated by exhaust gases. Upon entry, heating coils in the precombustion chamber then further heated the air and heated fuel also injected into the precombustion chamber prior to entry into the main vortex combustion chamber. The entry of the fuel-air mixture into the main vortex combustion chamber was such that a very large swirl was created which helped ensure proper mixture and a substantially uniform combustion within the combustion chamber.

In recent years, due to the cost of fuel and due to concern for the environment, there has been a high interest in the use of biofuels. Biofuels can include solid, liquid, or gas fuel derived from recently expired biological material. Biofuel can be produced from theoretically any biological carbon source, the most common of which include plants and plant-derived materials. The biofuel industry is expanding in Europe, Asia and the Americas. The most common use for biofuels is as liquid fuels for automotive transport. There is also, however, a desire in industry to use biofuel to generate steam at and/or electricity. Biodiesel is the most common biofuel in Europe, and is becoming more popular in Asia and America. Biodiesel can be produced from oils or fats, for example, using transesterification of vegetable oil, and forms into a liquid similar in composition to petroleum diesel.

Biodiesel production can result in glycerol (glycerin) as a by-product; for example, at one part glycerol for every 10 parts biodiesel. This has resulted in a glut in the market for glycerol. Accordingly, rather than being able to sell the glycerol, many companies have to pay for its disposal. Sources indicate that the 2006 levels of glycerol production were at about 350,000 tons per annum in the USA, and 600,000 tons per annum in Europe. Sources further indicate that such levels will only increase as biodiesel becomes more popular as a homegrown energy source and as Europe implements EU directive 2003/30/EC, which requires replacement of 5.75% of petroleum fuels with biofuel, across all member states by 2010. Recognized, therefore, by the inventor is the need for and apparatus and methods of economically disposing of glycerin or other in an environmentally friendly and energy efficient manner.

Also recognized by the inventor is that, although considered a waste product of biodiesel fuel production, waste fuels, such as glycerin, have significant energy delivery potential. Glycerin, however, along with some other forms of waste/biofuels, have characteristics which must be overcome in order to employ them as a fuel source. For example, various forms of glycerol remain a solid below approximately 18° C. (64.4° F.), have a flashpoint of 199° C. (390.2° F.), and have an autoignition point of 412° C. (773.6° F.). In contrast, petroleum diesel is a liquid at room temperature and has a typical flashpoint of between approximately 52° C. (126° F.) and 96° C. (204° F.) and an autoignition point of approximately 210° C. (410° F.)—nearly half that of glycerin. Recognized, therefore, by the inventor is the need for an apparatus and methods for economically and efficiently burning such heavily viscous waste/biofuels in a combustion chamber to produce an exhaust which can be utilized as an energy source. Further recognized by the inventor is the need for such apparatus and methods which can provide flameless combustion to thereby decrease nitric oxide emissions and increase energy efficiency.

SUMMARY OF THE INVENTION

In view of the foregoing, various embodiments of the present invention advantageously provide an apparatus and methods for economically and efficiently burning viscous biofuels in a combustion chamber to produce an exhaust which can be utilized as an energy source. Various embodiments of the present invention also advantageously provide an apparatus and methods which include a vortex combustion chamber configured to provide flameless combustion to thereby decrease nitric oxide emissions and increase energy efficiency. Various embodiments of the present invention provide an apparatus and methods which improve upon the Jirnov vortex combustion chamber and precombustion chamber described in U.S. Pat. No. 5,839,270 by Jirnov et al., titled “Sliding-Blade Rotary Air-Heat Engine with Isothermal Compression of Air,” to more efficiently accommodate use of the more viscous fuels, such as glycerol.

Particularly, various embodiments of the present invention advantageously provide an apparatus for providing flameless combustion of a viscous fuel. According to an embodiment of the present invention, the apparatus includes a precombustion chamber adapted to heat and at least partially combust a primary fuel and a main combustion chamber adapted to combust the primary fuel. The precombustion chamber can include a cylindrical housing having an enclosed proximal end portion, an open distal end portion, and a substantially hollow main body extending therebetween and substantially enclosing a precombustion chamber cavity. The precombustion chamber can include at least one air injection inlet port extending through the body of the cylindrical outer housing and positioned to inject or otherwise deliver combustion air into the precombustion chamber and positioned to help induce a first stage vortex in the main body portion of the housing of the precombustion chamber. The precombustion chamber can also include at least one primary fuel nozzle positioned to inject primary fuel into the precombustion chamber, an igniter fuel nozzle positioned to inject ignition fuel into the precombustion chamber, an igniter positioned to ignite the igniter fuel, and a hollow cylindrical combustion stabilizer positioned within the precombustion chamber cavity to receive igniter fuel and primary fuel and to isolate the primary fuel from a portion of the combustion air when being heated with the igniter fuel.

The combustion stabilizer includes a proximal end portion, a distal end portion, and a main body portion extending between the proximal end portion and the distal end portion. The combustion stabilizer main body includes a large diameter sidewall spaced radially inward from the precombustion chamber housing to define an annulus therebetween and includes at least one air inlet aperture extending therethrough to receive a portion of the combustion air to thereby supply oxygen to the igniter fuel and to thereby initiate oxidation of the fuel within the combustion stabilizer. The distal end portion is in fluid communication with the combustion stabilizer main body and has a small diameter sidewall having a diameter substantially smaller than the large diameter sidewall of the main body. The distal end portion further includes an unobstructed distal end aperture for expelling heated primary fuel into the precombustion chamber cavity adjacent to the distal end portion of the precombustion chamber housing.

The main combustion chamber includes an, e.g., cylindrical or elliptical housing having an at least partially enclosed proximal end portion including an exhaust aperture, an enclosed distal end portion, and an elongate main body extending therebetween and substantially enclosing a main combustion chamber cavity. The main body can include an inner main body diameter and can have a main body axial length extending at least approximately twice the main body diameter. The main body axial length can have a preselected value preselected to provide a sufficient pyrolyzed fuel travel distance within the main combustion chamber based upon one or more fuel performance characteristics of the primary fuel. The main combustion chamber can also include a combination precombustion chamber exhaust outlet and main combustion chamber fuel-air mixture inlet (hereinafter “exhaust-inlet) located adjacent the proximal end portion of the main combustion chamber housing and extending through the main body of the main combustion chamber housing. The exhaust-inlet is positioned to receive the at least partially combusted primary fuel from the precombustion chamber and positioned (e.g., tangentially) to induce a second stage vortex within the main body of the main combustion chamber housing.

The main combustion chamber also includes a combustion exhaust tube or other form of conduit (e.g., Venture form) extending from, and interfaced with, the proximal end portion of the main combustion chamber housing, and extending coaxially along a same longitudinal axis as the main combustion chamber housing. The combustion exhaust tube or conduit includes an open distal end portion and an elongate main body extending between the open distal end portion of the combustion exhaust tube and the proximal end portion of the main combustion chamber housing. The distal end portion of the combustion exhaust tube extends axially within the main combustion chamber cavity to a location between a position distally forward of an axial midpoint position of the elongate main body of the main combustion chamber housing and a position located axially a distance of at least one exhaust tube main body diameter from the distal end portion of the main combustion chamber housing.

According to another embodiment of the present invention, an apparatus for providing flameless combustion of a fuel includes a main combustion chamber adapted to combust a primary fuel. The main combustion chamber includes a housing having a proximal end portion including an exhaust aperture, a distal end portion, and an elongate main body extending therebetween and substantially enclosing a main combustion chamber cavity. The main body has an inner main body diameter and a main body axial length. An exhaust-inlet extends through the main body of the main combustion chamber housing at an inlet location. The exhaust-inlet is positioned to receive at least partially combusted primary fuel from a precombustion chamber and is positioned to help induce a vortex within the main body of the main combustion chamber housing. According to a preferred configuration, the main body axial length extends distally from the inlet location a distance value approximately equal to or greater than that of the inner main body diameter. Particularly, the main body axial length has a preselected value preselected to provide a sufficient pyrolyzed fuel travel distance from the exhaust-inlet within the main combustion chamber cavity to exit based upon one or more fuel performance characteristics of the particular type/configuration of the primary fuel.

The main combustion chamber can further include a combustion exhaust conduit extending from and interfaced with the proximal end portion of the main combustion chamber housing and extending coaxially along a same longitudinal axis as the main combustion chamber housing. The combustion exhaust conduit can include an open distal end portion and an elongate main body extending between the open distal end portion of the combustion exhaust conduit and the proximal end portion of the main combustion chamber housing. Specifically, the distal end portion of the combustion exhaust tube can extend axially within the main combustion chamber cavity to a location between a position distally forward of an axial midpoint position of the elongate main body of the main combustion chamber housing and a position located axially a distance of at least one exhaust tube main body diameter from the distal end portion of the main combustion chamber housing. According to this configuration, the axial spacing of the distal end portion of the combustion exhaust conduit from the distal end portion of the main combustion chamber housing has a value approximately equal to or greater than that of at least one exhaust conduit main body diameter inner diameter.

Various embodiments of the present invention also provide methods of providing flameless combustion of a viscous fuel. According to an embodiment of the present invention, such a method can include the steps of inducing a first stage vortex in a primary fuel-air mixture within a main body of a precombustion chamber of a flameless combustor, receiving within a main body of a main combustion chamber of the flameless combustor the primary fuel-air mixture having a first stage vortex induced state, and inducing a second stage vortex in the received primary fuel-air mixture to form a complex vortex pattern to thereby enhance flameless oxidation of the primary fuel within the main body of the main combustion chamber. According to a preferred configuration, the step of inducing can include expelling the primary fuel-air mixture tangentially into the main combustion chamber cavity through a precombustion chamber exhaust outlet. According to this configuration, the diameter of the first stage vortex is substantially smaller than a diameter of the second stage vortex formed within the main combustion chamber.

The method can also include the steps of interfacing with the main combustion chamber, a precombustion chamber adapted to heat and at least partially combust the primary fuel, igniting a secondary fuel within the precombustion chamber adjacent a flowpath of the primary fuel to at least partially combust the primary fuel within the precombustion chamber, sensing a temperature of the exhaust gas exiting the combustion exhaust conduit of the main combustion chamber, and controlling a flow of the secondary fuel into the precombustion chamber responsive to the exhaust gas temperature of the exhaust gas exiting the combustion exhaust conduit.

According to another embodiment of the present invention, a method of providing flameless combustion of a viscous fuel can include the steps of providing a main vortex combustion chamber of a flameless combustor having a main body substantially enclosing a main combustion chamber cavity having an axial length approximately equal to or greater than an inner diameter of the main combustion chamber cavity, and inducing a vortex within the main combustion chamber cavity to enhance flameless oxidation of a primary fuel. The method can also include the step of providing a combustion exhaust conduit within and axially coincident with the main combustion chamber cavity. The combustion exhaust conduit can have an inlet positioned at a location between an axial position distally forward of an axial midpoint position of the elongate main body of the main combustion chamber housing and an axial position within the main combustion chamber cavity adjacent the distal end portion of the main combustion chamber housing. The axial spacing of the distal end portion of the combustion exhaust conduit from an inner surface of the distal end portion of the main combustion chamber housing can further have a value approximately equal to or greater than that of at least one exhaust conduit main body inner diameter.

The method can further include the step of injecting the primary fuel into the main combustion chamber cavity through a combination precombustion chamber exhaust outlet-main combustion chamber inlet (“exhaust-inlet”). The exhaust-inlet is axially spaced apart from the combustion exhaust conduit inlet a preselected value preselected to provide a sufficient pyrolyzed fuel travel distance from the exhaust-inlet within the main combustion chamber cavity based upon one or more fuel performance characteristics of the primary fuel to provide substantially complete pyrolization thereof. The method can further include the step of preselecting the value of the axial separation between the exhaust-inlet and the combustion exhaust conduit inlet to provide the sufficient pyrolyzed fuel travel distance from the exhaust-inlet within the main combustion chamber cavity responsive to one or more fuel performance characteristics of the glycerol fuel.

Various embodiments of the present invention also provide a precombustion chamber, and a vortex combustion chamber which is an improvement over the Jirnov vortex combustion chamber and precombustion chamber. Various embodiments of the present invention provide, for example, a vortex combustor including a main combustion chamber connected or otherwise interfaced with a precombustion chamber, which successfully solves problems associated with operating on highly viscous fuels with a high completeness of combustion over the wide range of the coefficient of air redundance and produces a substantial reduction in toxicity of exhaust gases. Various embodiments of the present invention provide high thermal and volumetric efficiency, may employ a variety of types of viscous and non-viscous combustible hydrocarbon fuels, have reduced quantities of environmentally damaging emissions, and have a simplified combustor design and ease of fabricating, which is economical to manufacture in mass production and is inexpensive to operate, service, and repair.

Various embodiments of the present invention provide a vortex chamber positioned at the tube inlet and provide feedback loops positioned along the length of the heat transfer section, which enable the resulting fuel combustion efficiency to be increased by inducing a swirl flow and intensive recirculation of fluid along the length of the heat transfer section. Such improved fuel efficiency can advantageously reduce environmentally damaging emissions. Further, such apparatus may be used in converting thermal energy into electric power, can be used in generating steam, and/or can be utilized as part of a transportation engine with high thermal efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the features and advantages of the invention, as well as others which will become apparent, may be understood in more detail, a more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings, which form a part of this specification. It is to be noted, however, that the drawings illustrate only various embodiments of the invention and are therefore not to be considered limiting of the invention's scope as it may include other effective embodiments as well.

FIG. 1A is a partially perspective and partially sectional view of a combustor for providing flameless combustion of a viscous fuel according to an embodiment of the present invention;

FIG. 1B is a partially prospective and partially sectional view of the combustor of FIG. 1A illustrating vortex generation according to an embodiment of the present invention;

FIG. 2A is a sectional view of the combustor taken along the 2-2 line of FIG. 1B according to an embodiment of the present invention;

FIG. 2B is a sectional view of the combustor of FIG. 2A illustrating vortex generation according to an embodiment of the present invention;

FIG. 3A is a sectional view of the main combustion chamber of FIG. 1A according to an embodiment of the present invention;

FIG. 3B is a sectional view of an alternate embodiment of the main combustion chamber of FIG. 1A according to an embodiment of the present invention

FIG. 4 is a sectional view of an alternate embodiment of the combustor illustrated in FIG. 2B according to an embodiment of the present invention;

FIG. 5 is a sectional view of an alternate embodiment of the combustor illustrated in FIG. 1B according to an embodiment of the present invention;

FIG. 6A is a sectional view of an alternate embodiment of the combustor illustrated in FIG. 2A an embodiment of the present invention;

FIG. 6B is a sectional view of an alternate embodiment of the combustor illustrated in FIG. 2A an embodiment of the present invention;

FIG. 7 is a schematic block diagram of a combustion management/fuel-gas supply system for providing flameless combustion according to an embodiment of the present invention;

FIG. 8 is a schematic block flow diagram illustrating a method of providing flameless combustion including steps for forming the combustor of FIG. 1A according to an embodiment of the present invention;

FIG. 9 is a schematic block flow diagram illustrating a method of providing flameless combustion including steps for operating the combustor of FIG. 1A according to an embodiment of the present invention;

FIG. 10 is a schematic block flow diagram illustrating substeps of the method shown in FIG. 9 according to an embodiment of the present invention; and

FIG. 11 is a schematic block flow diagram illustrating substeps of the method shown in FIG. 9 according to an embodiment of the present invention.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, which illustrate embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.

FIGS. 1A-11 illustrate a system 30 including combustor apparatus 31 and methods which improve upon the vortex combustion chamber and precombustion chamber of the Jirnov engine described in U.S. Pat. No. 5,839,270 by Jirnov et al., titled “Sliding-Blade Rotary Air-Heat Engine with Isothermal Compression of Air,” to more efficiently accommodate use of more viscous fuels. According to various embodiments of the present invention, the combustor apparatus 31 can beneficially work under high pressure and high flow rate of air. The combustor apparatus 31 can be especially useful for burning waste fuel, such as Glycerol (Glycerin), and emulsified heavy oil (with water) fuels, along with a number of conventional liquid fuels, such as jet propellant (JP), Diesel, Kerosene, Gasoline, and any of the gaseous fuels, such as Hydrogen, CO and Carbohydrate, etc. Various embodiments of the combustor apparatus 31 provide substantially complete combustion with very low nitric oxide (NOx) and carbon monoxide (CO). Embodiments of the combustor apparatus 31 further provide no flame on the exit, making it an ideal apparatus for use in gas turbines and in heating systems.

More specifically, as perhaps best illustrated in FIGS. 1A and 2A, the apparatus 31 can include a vortex precombustion chamber 33 interfaced with a main vortex combustion chamber 35 as will be described in more detail, below. The precombustion chamber 33 is used for forming, a super-rich fuel and air mixture, ignition, partial combustion and pyrolysisation of heavy and low grade fuels. Note, FIGS. 3B-6A illustrate various alternative embodiments of the apparatus 31, particularly with respect to how the vortex precombustion chamber 33 is interfaced with the main vortex combustion chamber 35. For simplicity, the same numbering will be maintained for like items across the various embodiments.

As shown in FIG. 2A, according to an embodiment of the present invention, the precombustion chamber 33 has a hollow cylindrical housing 41 enclosing a cavity 42 at one end 43, and can have one or more air inlets 45 extending through its sidewall (main body) 47. A hollow cylindrical combustion stabilizer 49 is secured within the outer housing 41 and can have a large diameter side wall 51 spaced radially inward from the outer housing 41 to define an annulus 53 therebetween, and can have a reduced diameter neck portion 55 at one end. At least one, but preferably a plurality of air inlet ports 57 extend through the larger diameter sidewall 51 to provide combustion air communication with the air inlet 45 of the outer housing 41. According to an embodiment of the precombustion chamber 33, the air inlet ports 57 extend tangentially through the sidewall 51.

According to an embodiment of the precombustion chamber 33, a funnel-shaped flame tube 61 is secured to the open end of the outer housing 41 by a radial flange 63 and has a hollow cylindrical side wall portion 65 received within the open end of the outer housing 41, a conical side wall portion 67, and a reduced diameter neck portion 69 at one end. The radial flange 63 is secured between the open end of the outer housing 41 and a conical flanged fitting 71 on the outer housing of the vortex combustion chamber 35. The conical side wall portion 67 of the flame tube 61 is received within the conical flanged fitting 71, and the reduced diameter neck portion 69 is connected with a tubular channel 73 disposed tangential to the periphery of the main vortex combustion chamber 35. The exterior of the cylindrical side wall portion 65 is spaced radially inward from the interior of the outer housing 41 and the conical side wall portion 67; and the reduced neck portion 69 is spaced radially inward from the interior of the conical flanged fitting 71 to define an annulus 75 therebetween. Further, a plurality of passageways 77 extend through the radial flange 63 to allow communication through the annulus 75.

According to an embodiment of the present invention, the combustion stabilizer 49 is provided with one or more primary fuel injectors/nozzles 81 for injecting a primary fuel, a secondary fuel injector(s)/nozzle(s) 83 for injecting a secondary or ignition fuel positioned to ignite the primary fuel, and a fuel igniter or spark plug 85. The secondary fuel injector 83 can provide fuel, e.g., propane, etc., to pre-heat the primary fuel, particularly if a heavy or viscous primary fuel is used or if the ambient temperature is below that required. According to a preferred configuration, the nozzles 81, 83, and the igniter 85 are located in the top cover portion 87 of the precombustion chamber 33. A portion of air from the general airflow drawn or injected through opening 45, is further drawn or injected into the combustion stabilizer 49 through air inlets 57 to create an air-fuel mixture near the secondary fuel injector 83 and the spark plug 85.

According to another embodiment of the present invention, as perhaps best illustrated in FIG. 4, rather than utilize a secondary or ignition fuel, the combustion stabilizer 49 is instead provided with a fuel vaporizer 91 having terminals 93 extending from the precombustion chamber 33, which are connected with a source of electrical current (not shown). A portion of air from the general airflow drawn or injected through opening 45 is further drawn into the combustion stabilizer 49 through air inlets 57 to create an air-fuel mixture near the spark plug 85. Such fuel vaporizer 91 provides an alternative methodology of preheating the primary fuel in cold seasons and/or if a heavy or viscous fuel is used. That is, low-grade or waste fuels, when used, can be pre-heated/combustion to reduce the viscosity of the fuel and to provide for an acceptable level of atomization.

According to an embodiment of the present invention, in operation, fuel is delivered to the precombustion chamber 33 through single or multiple primary fuel injector(s)/nozzle(s) 81 via a fuel supply system 37. When multiple nozzles 81 are utilized, the fuel supply system 37 can beneficially allow the apparatus 31 to oxidize different types of liquid or gaseous fuels emanating from independent sources, separately or simultaneously. The fuel nozzle or nozzles 81 can be interfaced with a compressed air/gas supply, either directly or indirectly via taps (not shown) in the fuel supply lines 39, to help breakup the liquid fuel jet expelled from the fuel nozzle(s) 81 and provide a minimal size of fuel droplets, i.e., form an aerosol or colloid, or at least a suspension. The resulting minimal size droplets can have a reduced (short) time of vaporization, and thus, reduced combustion time. This can be especially beneficial when combustion for waste fuels, such as Glycerin, is desired.

As noted above, combustion airflow, for example, provided by a cooling air (gas/fluid) supply system 36, is provided through the one or more air inlets 45 extending through sidewall 47. The required airflow rate and/or oxygen content of the combustion air can be determined and set based on the ratios of momentum and mass for a given liquid fuel flow rate to provide maximum instability of the air-fuel flow and efficient precombustion. Particularly, the combined airflow rate of the air entering/exiting the inlet(s) 45 and mass flow of primary fuel entering the precombustion chamber 33 can have a ratio between 20:1 to 40:1, with a preferred ratio of approximately 30:1; and the combustion gas (e.g., air) to mass flow of fuel can have a ratio of preferably between 30:1 to 50:1, with a more preferred ratio of approximately 40:1. Such fuel injection configuration can provide for the shortest breakup length and breakup time inside of the precombustion chamber 33. Further, the precombustion chamber 33 can have an axial length to sidewall/main body cross-sectional diameter ratio of preferably between 2:1 to 4:1, with a more preferred ratio of approximately 3:1 to ensure sufficient precombustion prior to entering the main vortex combustion chamber 35. Consequently, according to embodiments of the apparatus 31, the combustion process is complete and occurs downstream inside of the main chamber 35 without flame on the exit. The absence of a flame on exit can beneficially extend the use of apparatus 31/vortex combustion chamber 35 for many applications known to those skilled in the art, including for turbines, engines, and heaters.

As perhaps best shown in FIG. 7, process control of apparatus 31 can be provided by a combustion management/fuel-gas supply system 200 which can include a controller 201 positioned to sense various fuel system and combustion system parameters to control the combustion process. The controller 201 can include a processor/logic circuit 203 and memory 205 coupled to the processor 203 to store software and/or database records therein. The memory 205 can include volatile and nonvolatile memory known to those skilled in the art including, for example, RAM, ROM, and magnetic or optical disks, just to name a few.

The combustion management/fuel-gas supply system 200 can also include various sensors, known to those skilled in the art, including, for example, a mass flow/density/momentum meter or meters 211 interfaced with the fuel system 37 to monitor fuel characteristics of the primary fuel; a combustion air pressure sensor 213 positioned to monitor air pressure of the air entering air inlet or inlets 45; a combustion air oxygen content sensor 215 positioned to monitor the oxygen content of the combustion air; and an exhaust gas temperature (EGT) probe 217 positioned to sense the temperature of the exhaust gases emanating from combustion exhaust tube or conduit 115 (see FIG. 1A), described in more detail later.

The combustion management/fuel-gas supply system 200 can further include various control devices including, for example, a combustion air/gas pump, injector, or valve 221 for adjusting combustion air pressure; a primary fuel pump or valve 223 for managing fuel pressure of the primary fuel; a secondary fuel control pump or valve 225 for managing the amount of secondary fuel used to help pre-combust the primary fuel in the combustion stabilizer 49 of the precombustion chamber 33; an ignition circuit 227 for igniting the secondary fuel; and an fuel-air pump 229 for aerating the primary fuel. Note, it should be understood by one skilled in the art that the above described control devices can further include internal controllers within each device.

The combustion management/fuel-gas supply system 200 can also include a user interface 207 as known to those skilled in the art, to provide a user access to manipulate or access software and database records, and combustion management program product 231 stored in memory 205 of the controller 201 to provide combustion management. The program product 231, according to an embodiment of the combustion management/fuel-gas supply systems 200 includes instructions that when executed by the controller 201 cause the controller to perform various operations to include gathering or otherwise collecting real-time data from sensors 211, 213, 215, and 217, to perform real-time combustion management to include, for example: adjusting fuel pressure of the primary fuel responsive to output requirements of a supported system (e.g., turbine, engine, etc.); adjusting combustion air pressure/rate to maximize instability of the air-fuel flow and/or adjusting aeration of the fuel responsive to the density or mass flow of the primary fuel to enhance combustibility of the fuel; and applying or discontinuing application of the secondary fuel responsive to the exhaust gas temperature to help ensure substantially complete oxidation of the primary fuel prior to exit from the main combustion chamber exhaust conduit 115, just to name a few.

Note, the combustion management program product 231 can be in the form of microcode, programs, routines, and symbolic languages that provide a specific set for sets of ordered operations that control the functioning of the hardware and direct its operation, as known and understood by those skilled in the art. Note also, the combustion management program product 231, according to an embodiment of the present invention, need not reside in its entirety in volatile memory, but can be selectively loaded, as necessary, according to various methodologies as known and understood by those skilled in the art.

As shown in FIGS. 2A-2B, for example, the main vortex combustion chamber 35 receives through a joint precombustion chamber exhaust outlet and main combustion chamber fuel-air inlet (or “exhaust-inlet”) 95, a super-rich mixture of fuel and air formed in the precombustion chamber 33 along with partially burned and pyrolyzed products for after-burning. As perhaps best shown in FIGS. 3A-3B, according to an embodiment of the present invention, the main combustion chamber 35 has an outer housing formed by a main body 101, 101′, enclosed at the bottom end by outer bottom end wall 103, and at the top end by an outer top wall 105 and a collector member 107 secured to the outer top wall 105, to form a combustion chamber cavity 109 therein in which nameless combustion occurs. The collector member 107 has a top flange 111 and a central bore 113 which can be connected to or otherwise interfaced with the inlet port of a powered/heated device, e.g., gas turbine, engine, etc. (not shown).

According to various embodiments of the present invention, the main body 101 of the main combustion chamber 35 preferably has a cylindrical form (FIG. 3A), an elliptical form (see, e.g., FIG. 3B) or a funnel shaped form (not shown), although other forms/configurations are within the scope of the present invention. The main combustion chamber 35 also has an axial length preselected based on the type of fuel expected to be combusted. For example, for a heavily viscous fuel such as glycerol, the main combustion chamber cavity 109 can have an axial length to main body cross-sectional diameter ratio sufficient to provide uniform volume distributed combustion for the type of fuel used. In the exemplary configuration, the main combustion chamber cavity 109 can have an axial length of at least half the diameter of the main combustion chamber cavity 109, and more preferably, an axial length equivalent to the value of at least one chamber cavity diameter, with the overall main combustion chamber cavity 109 preferably having at least an axial length of 1.5 or more chamber cavity diameters, and more preferably at least a length of two or more chamber cavity diameters. In a more preferred configuration, where glycerol is the fuel, the main body axial length to cross-sectional diameter ratio is preferably between 5:1 to 6:1, with a preferred ratio of approximately 5:1.

According to embodiments of the present invention, the main combustion chamber 35 further includes a combustion exhaust tube or conduit 115, which serves as the outlet or exhaust pipe for the near-axis zone of the main vortex combustion chamber 35. The exhaust conduit 115 can be configured either as a separate unit, or as a tubular extension of collector member 107, which extends distally therefrom through a central opening 117 in the inner top wall 105. The combustion exhaust conduit 115 and central opening 117 together form an annulus 119 therebetween. The combustion exhaust conduit 115 can have various shapes to include cylindrical (see, e.g., FIG. 3A), venturi (see, e.g., FIG. 3B) shown at 115′, or others known to those skilled in the art.

According to an embodiment of the present invention, the combustion exhaust tube or conduit 115 is positioned and extends within the main combustion chamber cavity 109 to a location, for example, at least beyond the midpoint of the main body 101 of the combustion chamber 35, but preferably adjacent the bottom end wall 103 spaced apart therefrom at an axial distance equivalent to at least the value of the inner diameter of a distal/inlet portion 11.6 of the combustion exhaust conduit 115. When heavily viscous fuel such as glycerol is used, which requires additional time to oxidize, the combustion exhaust tube or conduit 115 can have a axial offset distance from the inner surface of the bottom end wall 103 to combustion exhaust tube cross-sectional inner diameter ratio of between 1:1 to 3:1, with a preferred ratio of approximately 2:1. As perhaps best shown in FIG. 3A, according to a preferred embodiment of the present invention, the exhaust conduit 115 can extend axially approximately 75% of the main body 101 (e.g., cylindrical part) of the vortex combustion chamber 35, making the axial offset distance approximately 25% of the axial length of the main body 101.

Accordingly, for the main combustion chamber 35 configuration having a main combustion chamber cavity 109, combustion exhaust conduit 115, and precombustion chamber 33 positioned, for example, as shown in FIG. 1B, the pyrolyzed gases entering the main combustion chamber cavity 109 from precombustion chamber 33 must travel at least twice the distance through the vortex combustion chamber 35 as that of the Jirnov vortex combustion chamber before it can initiate escape through the combustor exhaust conduit 115. Further, any remaining fuel inside the combustor exhaust conduit 115 also must travel at least approximately twice the distance before exiting the combustor exhaust conduit 115 as that of the Jirnov vortex combustor to further allow any remaining fuel to oxidize before exit through the exhaust port 113. As such, the pyrolyzed gases entering the main combustion chamber cavity 109 from precombustion chamber 33 must ultimately travel four or five times the total distance to exit through the exhaust orifice or port 113. Even in an embodiment of the present invention such as, for example, that shown in FIG. 5 having the joint precombustion chamber exhaust outlet-main combustion chamber inlet 95 positioned, for example, at a midpoint or some other medial position, the ultimate travel distance is at least two or more times the total distance to exit through the exhaust orifice or port 113.

According to an embodiment of the present invention, an inner bottom wall 121 and an inner top wall 123 are secured within the outer bottom wall 103 and outer top wall 105, respectively, in a spaced apart relation to define a flow passageway 125 therebetween. One or more swirl nozzles 127 are connected to or otherwise interfaced with the passageway 125 between the outer bottom wall 103 and inner bottom wall 121. A plurality of passageways 129 extend longitudinally through the side wall of the cylindrical main body 101 of the combustion chamber housing to allow communication with the flow passageways 131. The passageways 125, 129, and 131, form an isolated fuel-air recirculation channel which passes around the interior of the main combustion chamber 35.

According to an embodiment of the present invention, a bypass conduit 133 connects the radial passageways 131 to a compressed airflow entering the recirculation system of combustion chamber 35 via an external supply conduit 135. According to a preferred configuration, the recirculation system via bypass conduit 133 and external supply conduit 135 receives both cooling air and another cooling fluid (e.g., water) to enhance cooling the main combustion chamber 35.

As perhaps best shown in FIGS. 2A and 3A, the main combustion chamber 35 can include a perforated liner 141 having openings 143. The liner 141 can be secured to the interior surfaces of the main body (sidewall) 101, inner bottom wall 121, and inner top wall 123 of the combustion chamber 35. The vertically opposed interior surfaces of the liner 141 and the inner top wall 123 and inner bottom wall 121 have opposite facing, outwardly concave, curved surfaces with the axial distance between the curved surfaces increasing inversely from their periphery with respect to the radial distance. According to an embodiment of the combustion chamber 35, the vertically opposed interior surfaces of the liner 141 are curved or contoured according to the Navier-Stocks' equation with the constraint to provide substantially constant vortex radial velocity conditions to ensure minimal hydrodynamic losses.

The liner 141 includes a cylindrical side wall 145 joined tangentially to the tubular channel 73 (see, e.g., FIG. 2A) and serves as a cylindrical heat tube between the precombustion chamber 33 and the main combustion chamber 35. An annulus/gap 147 between the inner surface of the main body 101 of the combustion chamber 35 and cylindrical side wall 145 of the liner 141, and between the inner surface of the inner bottom wall 121 and inner surface of the inner top wall 123 and the perforated liner 141, serves as a cooling jacket. The annulus/gap 147 is in communication with the annulus 75 (see, e.g., FIG. 2A). According to an embodiment of the main combustion chamber 35, the juncture of the combustor exhaust conduit 115 and the top flange 111 is contoured and has an annular raised lip ring 151 which extends angularly upwardly therefrom for a distance into the passageway 125 between the inner top wall 123 and outer top wall of the main combustion chamber 35.

The cool and moist air (identified above) can be directed through the bypass conduit 133 and the radial passageways 131, and onto the annular raised lip ring 151, which serves as a fuel-air ejector ring, and which causes a Ventura effect to return trapped fuel film through the recirculation channel 125, 129, 131 and swirl nozzle(s) 127 back into the chamber combustion zone. The swirl nozzle(s) 127 are configured to swirl the recirculated fuel-air-water mixture flowing through the recirculation channels 125, 129, 131, as it enters the interior of the main combustion chamber 35. Because the swirl nozzle or nozzles 127 are located in the near-axis zone of the vortex combustion chamber 35 where the lowest pressure tends to occur, the fuel-air ejector ring 151 is subjected to a substantial pressure drop and its operation is thus intensified.

To initiate combustion of a primary fuel (e.g., glycerin), in the embodiment shown in FIG. 2A, secondary or ignition fuel (e.g., propane, etc.) is introduced next to secondary fuel nozzle 83, and the igniter/sparkplug 93 is momentarily activated to ignite the ignition fuel. Combustion air/gas is drawn or pumped into the precombustion chamber 33 through air/gas inlet(s) 45. The primary fuel is then introduced into the combustion stabilizer 49 through the primary fuel injector(s) 81, along with a portion of the combustion air/gas from the general air/gas flow and into the combustion stabilizer 49 through air openings/inlets 57, to create an air-fuel mixture near the secondary fuel nozzle 83, for ignition.

Similarly, in the embodiment shown in FIG. 4, the primary fuel is introduced into the combustion stabilizer 49 through the primary fuel injector(s) 81 and a portion of air from the general air flow is drawn into the stabilizer 49 through the openings/inlets 57 to create an air-fuel mixture near the spark plug 93, and the plug is activated to ignite the mixture. In this configuration, a fuel vaporizer 91 may used to heat the fuel, particularly if a heavy fuel is used in cold weather that does not require ignition by a more readily combustible secondary fuel.

As perhaps best shown in FIG. 2B, the ignited and partly pyrolyzed fuel-air mixture formed in the combustion stabilizer 49 then passes through the interior of the funnel-shaped flame tube 143, where it begins to swirl due to the orientation of the general air/gas flow and/or orientation of the primary and/or secondary fuel nozzles (first stage vortex 161 formation). The ignited and partially pyrolyzed fuel then passes through the channel 73, for example, tangentially through exhaust-inlet 95 and into the vortex combustion chamber 35 for after-burning (see FIGS. 1B, 2B and 4). Note, in an alternate embodiment of the present invention, perhaps best shown in FIG. 6A-6B, the precombustion chamber 33 can be instead interfaced with the combustion chamber 35 at exhaust-inlet 95′ in a more normal orientation. Other orientations, however, are also within the scope of the present invention.

The air received through air/gas inlet(s) 45 can also flow through the annulus 53, 75, and passageways 77 between the flame tube 61 and the housing 41 of the precombustion chamber 33 and conical flanged fitting 71 of the vortex combustion chamber 35 and the annulus 147 surrounding the perforated liner 141, to thereby cool the flame tube 61, perforated liner 141 and cylindrical side wall 145. According to an embodiment of the present invention illustrated in FIGS. 1A-2B, the combustion products of partially burned and pyrolyzed fuel from the precombustion chamber 33, already in a swirling state, are caused to swirl (to form a second stage vortex 163) as they enter the vortex combustion chamber cavity 109 through the tangential channel 73, thereby forming a two-stage complex vortex pattern. Note, in an alternate embodiment of the present invention, perhaps best shown in FIG. 6A-6B, whereby the precombustion chamber 33 is instead interfaced with the combustion chamber 35 in a more normal orientation, the combustion exhaust tube or conduit 115 can include a swirl enhancer 171, e.g., spiral, grooves or protuberances oriented to induce the swirling state within the combustion chamber cavity 109.

It is perhaps best shown in FIG. 3A, the inwardly contoured walls 121, 123, and liner 141 of the main combustion chamber cavity 109, and the equinoctial condition of the centrifugal and aerodynamic forces acting on the condensed particles in the vortex stream of air in the main combustion chamber cavity 109 allow unvaporized fuel droplets to be confined in equilibrium in the orbit of rotation for a sufficient length of time such that fuel droplet migration to a small radius will only occur when the droplet diameters become sufficiently small during the combustion process. This feature can enhance stabilizing combustion and providing a high degree of completeness of combustion.

In the combustion process, a portion of the fuel, not participating in mixing and combustion, moistens the inner walls of the liner 141 in the vortex combustion chamber 35, and in the form of a migrating film of unmixed and uncombusted fuel, migrates to the lower portion of the chamber 35, at least in part, due to gravity, and is captured at the inward side of the annular raised lip ejector ring 151. A portion of the preferably cool and moist air is directed through the conduit 135, the bypass conduit 133, and the radial passageways 131, onto the outward side of the annular raised lip ejector ring 151, which causes a venturi effect, which further functions to return the trapped unmixed and uncombusted fuel as a fuel-air mixture through the recirculation channels 125, 129, and swirl nozzle 127 back into the chamber combustion zone. The swirl nozzle 127 swirls the recirculated fuel-air mixture flowing through the recirculation channels 125, 129, as it enters the cavity 109 of the vortex combustion chamber 35.

Efficient and reliable cooling of the combustion chamber 35 can be provided by air flows through the annulus 75 and 147 and by the flowing of part of the cooling air (preferably with a certain amount of water) through recirculation channels 125, 129. As noted previously, because the swirl nozzle or nozzles 127 are located in the near-axis zone of the vortex combustion chamber where re-refraction occurs, in such configuration, the fuel-air ejector ring 151 is subjected to a substantial pressure drop, and its operation is intensified. The combined total amount of air arriving at the main vortex chamber combustion zone through air inlet ports 57, tubular channel 73, annulus 75, and bypass conduit 133, form a lean fuel-air mixture for after-burning.

Beneficially, the various combinations of the structural and operational features of embodiments of the main vortex combustion chamber 35 provide a small combustion chamber capable of burning a variety of fuels with high energy efficiency and low toxicity of the products, including low amounts of NOx. According to various embodiments of the present invention, the process of combustion, managed by controlling the supply of a super-rich air-fuel mixture in the precombustion chamber 31, supply of a lean mixture in the vortex chamber cavity 109, and the introduction of a certain amount of water into the combustion zone, can help ensure a sufficiently low temperature of combustion, which is typically the significant, if not dominant, factor in decreasing the NOx content in exhaust gases, but that is also sufficiently high enough to prevent escape of other unwanted or toxic exhaust gases.

Embodiments of the present invention also include methods for providing flameless combustion of a fuel, in general, and for a heavy viscous waste fuel, such as glycerol, in particular. According to an embodiment of the present invention, such a method can include forming a combustor apparatus 31 including a precombustion chamber 33 and a main combustion chamber 35 (see, e.g., FIG. 8), and controlling combustion (oxidation) of the fuel to produce heat and/or to dispose of a waste fuel (see, e.g., FIG. 9), which can include controlling aeration of the primary fuel, controlling the flow of the secondary fuel into the precombustion chamber 33 (see, e.g., FIG. 10), and controlling primary combustion airflow and primary combustion fuel flow (see, e.g., FIG. 11).

As perhaps best shown in FIG. 8, the combustor apparatus 31 can be formed by performing the steps of providing a main vortex combustion chamber 35 having a main body 101 substantially enclosing a main combustion chamber cavity 109 (block 301), and interfacing a precombustion chamber 33 adapted to heat and at least partially combust the primary fuel with the main combustion chamber (block 303). The step of providing a main vortex combustion chamber 35 can include the substeps of: preselecting the value of an axial length of a main combustion chamber cavity (block 305); preselecting the value of an axial separation between a primary fuel inlet 95 and the distal inner surface of the main combustion chamber cavity 109 (block 307); preselecting the value of an axial separation between a primary fuel inlet and a combustion exhaust conduit inlet (block 309); and preselecting the value of an axial separation between the inlet of a combustion exhaust conduit 115 and the distal inner surface of the main combustion chamber cavity 109 (block 311), in response to or otherwise based upon an amount of time necessary to sufficiently combust the primary fuel, which is further based upon fuel characteristics including viscosity, mass flow, density, and in the end temperature of the primary fuel expected to be utilized (combusted) in the combustor apparatus 31.

As perhaps best shown in FIG. 9, the combustion/oxidation of the primary fuel can be controlled by inducing a first stage vortex 161 in a primary fuel-air mixture within the main body 47 of precombustion chamber 33 (block 321); receiving the primary fuel having the first stage vortex induced state within the main body 101 of the main combustion chamber 35 (block 323); inducing a second stage vortex 163 in the received primary fuel-air mixture to form a complex vortex pattern (block 325) which can include expelling the partially combusted fuel in the primary fuel-air mixture into the main combustion chamber cavity 109 through a combination precombustion chamber exhaust outlet and main combustion chamber fuel-air inlet 95, 95′ (block 327); and combusting (oxidizing) the primary fuel to produce heat and/or to dispose of a “waste” primary fuel.

As perhaps best shown in FIG. 10, the step of inducing a first stage vortex 161 can include the substeps of: aerating the primary fuel prior to entry into the precombustion chamber 33 to minimize a size of fuel droplets entering the precombustion chamber (block 331); igniting a preferably gas-type secondary fuel within the precombustion chamber 33 adjacent a flowpath of the primary fuel to at least partially combust the primary fuel within the precombustion chamber 33 (block 333); sensing a temperature of the exhaust gas exiting the combustion exhaust conduit of the main combustion chamber (block 335); and controlling the flow of the secondary fuel into the precombustion chamber 33 responsive to the exhaust gas temperature of the exhaust gas exiting the combustion exhaust conduit 115 (block 337). Further, as perhaps best shown in FIG. 11, the step of inducing the first stage vortex 161 can further include the substeps of sensing massflow, density, and/or momentum of the primary fuel (block 341), and controlling the primary combustion fuel flow rate and/or pressure, and correspondingly, the combustion airflow rate and/or pressure (block 343).

This patent application is related to U.S. Provisional Application No. 61/052,076 by Anatoli Borissov, filed May 9, 2008, titled “Apparatus And Methods For Providing Uniformly Volume Distributed Combustion of Fuel and U.S. Pat. No. 5,839,270 by Jirnov et al., titled “Sliding-Blade Rotary Air-Heat Engine with Isothermal Compression of Air,” incorporated by reference in its entirety.

In the drawings and specification, there have been disclosed a typical preferred embodiment of the invention, and although specific terms are employed, the terms are used in a descriptive sense only and not for purposes of limitation. The invention has been described in considerable detail with specific reference to these illustrated embodiments. It will be apparent, however, that various modifications and changes can be made within the spirit and scope of the invention as described in the foregoing specification. 

1. An apparatus for providing flameless combustion of a viscous fuel, the apparatus comprising: a precombustion chamber adapted to heat and at least partially combust a primary fuel, the precombustion chamber including: an outer housing having an enclosed proximal end portion, an open distal end portion, and a substantially hollow main body portion extending therebetween and substantially enclosing a precombustion chamber cavity, at least one air injection inlet port extending through the main body portion of the outer housing and positioned to inject combustion air into the precombustion chamber, the at least one air injection inlet port further positioned to induce a first stage vortex in the main body portion of the housing of the precombustion chamber, at least one primary fuel nozzle positioned to inject the primary fuel into the precombustion chamber, an igniter fuel nozzle positioned to inject ignition fuel into the precombustion chamber, and a hollow cylindrical combustion stabilizer positioned within the precombustion chamber cavity to receive igniter fuel and primary fuel and to isolate the primary fuel from a portion of the combustion air when being heated with the igniter fuel, and having a proximal end portion, a distal end portion, and a main body portion extending between the proximal end portion and the distal end portion, the combustion stabilizer main body portion comprising a large diameter sidewall spaced radially inward from the precombustion chamber housing to define an annulus therebetween and having at least one air inlet aperture extending therethrough to receive a portion of the combustion air to thereby supply oxygen to the igniter fuel and to thereby initiate oxidation of the fuel within the combustion stabilizer, the distal end portion in fluid communication with the combustion stabilizer main body portion and having a small diameter sidewall having a diameter substantially smaller than the large diameter sidewall of the main body, the distal end portion of the combustion stabilizer further having an unobstructed distal end aperture for expelling heated primary fuel into the precombustion chamber cavity adjacent to the distal end portion of the precombustion chamber housing; and a main combustion chamber adapted to combust the primary fuel, the main combustion chamber including: a housing having an at least partially enclosed proximal end portion including an exhaust aperture, an enclosed distal end portion, and an elongate main body extending therebetween and substantially enclosing a main combustion chamber cavity, the main body having an inner main body diameter and having a main body axial length extending at least approximately twice the main body diameter, the main body axial length having a preselected value preselected to provide a sufficient pyrolyzed fuel travel distance within the main combustion chamber based upon one or more fuel performance characteristics of the primary fuel to provide substantially complete pyrolization thereof, an exhaust-inlet located adjacent the proximal end portion of the main combustion chamber housing and extending through the main body of the main combustion chamber housing, and positioned to receive the at least partially combusted primary fuel from the precombustion chamber and to induce a second stage vortex within the main body of the main combustion chamber housing, and a combustion exhaust tube extending from and interfaced with the proximal end portion of the main combustion chamber housing and extending coaxially along a same longitudinal axis as the main combustion chamber housing, and having an open distal end portion and an elongate main body extending between the open distal end portion of the combustion exhaust tube and the proximal end portion of the main combustion chamber housing, the distal end portion of the combustion exhaust tube extending axially within the main combustion chamber cavity to a location between a position distally forward of an axial midpoint position of the elongate main body of the main combustion chamber housing and a position located axially a distance of at least one exhaust tube main body diameter from the distal end portion of the main combustion chamber housing.
 2. An apparatus as defined in claim 1, wherein the primary fuel is viscous at ambient supply temperature, the apparatus further comprising a primary fuel supply system to provide the primary viscous fuel for combustion, the primary fuel supply system including: a compressed gas injector connected to a portion of the primary fuel supply system to form at least a suspension to thereby minimize a size of fuel droplets exiting the at least one primary fuel nozzle; a temperature sensor positioned to detect an exhaust gas temperature of the exhaust gas exiting the combustion exhaust tube; and a logic circuit positioned to control a flow of the igniter fuel into the precombustion chamber responsive to the exhaust gas temperature of the exhaust gas exiting the combustion exhaust tube.
 3. An apparatus as defined in claim 1, wherein a diameter of the second stage vortex is substantially larger than the diameter of the first stage vortex.
 4. An apparatus as defined in claim 1, wherein the pre-combustion chamber housing has an axial length to main body cross-sectional diameter ratio of between 2.5:1 to 4:1; and wherein the combustion air to mass flow of the primary fuel has a ratio of between 35:1 to 45:1.
 5. An apparatus as defined in claim 1, wherein the combined airflow rate of the combustion air entering the precombustion chamber is set based upon predetermined ratios of momentum and mass flow of primary fuel for a given fuel flow rate defining an air-fuel flow to thereby enhance instability of the air-fuel flow.
 6. An apparatus as defined in claim 1, wherein the primary fuel is glycerin; wherein the housing of the pre-combustion chamber is of a substantially cylindrical shape; wherein the housing of the main combustion chamber is of a substantially cylindrical shape; wherein the combustion exhaust tube has a configuration comprising one or more of the following: a cylindrical shape and a venturi shape; and wherein the combined airflow rate of the air exiting the at least one air inlet port and mass flow of primary fuel entering the precombustion chamber has a ratio between 20:1 to 40:1 to thereby enhance instability of the air-fuel flow.
 7. An apparatus as defined in claim 1, wherein the primary fuel is glycerin; and wherein a shape of the main body of the main combustion chamber housing is configured to provide a uniform temperature and pressure distribution inside of the main combustion chamber cavity and to optimize a pressure drop adjacent the open distal end portion of the combustion exhaust tube.
 8. An apparatus as defined in claim 1, wherein the primary fuel is glycerin; wherein the main combustion chamber cavity has an axial length to main body cross-sectional diameter ratio of between 4:1 to 6:1; and wherein the combustion exhaust tube has an axial offset distance from the distal end portion of the housing of the main combustion chamber-to-combustion exhaust tube cross-sectional diameter ratio of between approximately 1.5:1 to 2.5:1.
 9. An apparatus as defined in claim 1, wherein the main combustion chamber housing further includes an annulus extending between the proximal end and distal end portions of the housing; and wherein the distal end portion of the main combustion chamber housing includes a passageway extending from and in communication with the annulus and a plurality of swirl nozzles positioned to supply a cooling fluid to a portion of the cavity of the housing adjacent the distal end of the combustion exhaust tube, the cooling fluid including oxygen and trapped fuel film extracted from within the cavity adjacent the proximal end portion of the housing, the nozzles oriented to enhance instability of the fuel flow adjacent the distal end of the combustion exhaust tube.
 10. An apparatus as defined in claim 1, wherein the main combustion chamber further comprises a perforated liner secured to interior surfaces of the outer housing, inner bottom wall and inner top wall, the portion of the liner adjacent the inner bottom wall and inner top wall having an arc configured to provide constant vortex radial velocity conditions to thereby provide minimal hydrodynamic losses and to thereby confine unvaporized fuel droplets in equilibrium in an orbit of rotation of the second stage vortex stream; wherein the apparatus further comprises: a cooling air supply system to provide a fluid to cool inner surfaces of the main combustion chamber housing and to provide the fluid to the plurality of swirl nozzles to thereby enhance instability of the fuel flow adjacent the distal end of the combustion exhaust tube, and a recirculation passageway extending between the proximal end and distal end portions of the housing positioned to return trapped fuel film received from a portion of the cavity of the housing adjacent the proximal end of the combustion exhaust tube; and wherein the at least partially enclosed proximal end portion of the main combustion chamber housing includes an annular raised lip ring extending into the recirculation passageway and configured to cause a venturi effect within the recirculation passageway.
 11. An apparatus for providing flameless combustion of a fuel, the apparatus comprising a main combustion chamber adapted to combust a primary fuel, the main combustion chamber including: a housing having a proximal end portion including an exhaust aperture, a distal end portion, and an elongate main body extending therebetween and substantially enclosing a main combustion chamber cavity, the main body having an inner main body diameter and having a main body axial length; and an exhaust-inlet extending through the main body of the main combustion chamber housing at an inlet location, and positioned to receive at least partially combusted primary fuel from a precombustion chamber and to induce a vortex within the main body of the main combustion chamber housing, the main body axial length extending distally from the inlet location a distance approximately equal to or greater than a value of the inner main body diameter.
 12. An apparatus as defined in claim 11, wherein the main body axial length has a preselected value preselected to provide a sufficient pyrolyzed fuel travel distance from the exhaust-inlet within the main combustion chamber cavity based upon one or more fuel performance characteristics of the primary fuel to provide substantially complete pyrolization thereof.
 13. An apparatus as defined in claim 11, wherein the main combustion chamber further comprises: a combustion exhaust conduit extending from and interfaced with the proximal end portion of the main combustion chamber housing and extending coaxially along a same longitudinal axis as the main combustion chamber housing, and having an open distal end portion and an elongate main body extending between the open distal end portion of the combustion exhaust conduit and the proximal end portion of the main combustion chamber housing, the distal end portion of the combustion exhaust conduit extending within the main combustion chamber cavity to a location between a position distally forward of an axial midpoint position of the elongate main body of the main combustion chamber housing and a position axially adjacent to the distal end portion of the main combustion chamber housing, an axial spacing of the distal end portion of the combustion exhaust conduit from an inner surface of the distal end portion of the main combustion chamber housing having a value approximately equal to or greater than that of the inner diameter of the distal end portion of the exhaust conduit main body.
 14. An apparatus as defined in claim 13, wherein the exhaust-inlet is positioned normal to an inner surface portion of the main body of the main combustion chamber housing adjacent thereto; and wherein an outer surface of the combustion exhaust conduit includes a swirl enhancer comprising at least one of the following: a spiral recess extending along a substantial portion of the longitudinal length thereof, or a spiral protuberance extending along the substantial portion of the longitudinal length thereof, to thereby enhance the inducement of the vortex within the main body of the main combustion chamber housing.
 15. An apparatus as defined in claim 13, wherein the main body of the main combustion chamber housing has an axial length to main body cross-sectional inner diameter ratio of between approximately 4:1 to 6:1; and wherein the distal end portion of the combustion exhaust conduit has an axial offset distance from the distal end portion of the housing of the main combustion chamber to combustion exhaust conduit distal end portion cross-sectional diameter ratio of between approximately 5:1 to 2.5:1.
 16. An apparatus as defined in claim 11, wherein the vortex is a second stage vortex, the apparatus further comprising a precombustion chamber adapted to heat and at least partially combust the primary fuel, the precombustion chamber including: a housing having a proximal end portion, an open distal end portion, and a substantially hollow main body portion extending therebetween and having a substantially cylindrical inner surface substantially enclosing a precombustion chamber cavity; and at least one air injection inlet port extending through the main body portion of the precombustion chamber housing and positioned to inject combustion air into the precombustion chamber, the at least one air injection inlet port further positioned to induce a first stage vortex in the main body portion of the housing of the precombustion chamber.
 17. An apparatus as defined in claim 11, further comprising a precombustion chamber adapted to heat and at least partially combust the primary fuel, the precombustion chamber including: a housing having a proximal end portion, an open distal end portion, and a substantially hollow main body portion extending therebetween and ,substantially enclosing a precombustion chamber cavity; at least one primary fuel nozzle positioned to inject primary fuel into the precombustion chamber; an igniter fuel nozzle positioned to inject ignition fuel into the precombustion chamber; and a hollow combustion stabilizer positioned within the precombustion chamber cavity to receive the igniter fuel and the primary fuel and to isolate the primary fuel from a portion of the combustion air when being initially heated with the igniter fuel, and having a proximal end portion, a distal end portion, and a main body portion extending between the proximal end portion and the distal end portion, the combustion stabilizer main body portion comprising a large diameter sidewall spaced radially inward from the precombustion chamber housing to define an annulus therebetween and having at least one air inlet aperture extending therethrough to receive a portion of the combustion air to thereby supply oxygen to the igniter fuel and to thereby initiate oxidation of the fuel within the combustion stabilizer, the distal end portion of the combustion stabilizer in fluid communication with the combustion stabilizer main body and having a small diameter sidewall having a diameter substantially smaller than the large diameter sidewall of the main body, the distal end portion further having an unobstructed distal end aperture for expelling heated primary fuel into the precombustion chamber cavity adjacent to the distal end portion of the precombustion chamber housing.
 18. An apparatus as defined in claim 17, wherein a diameter of the second stage vortex is substantially larger than the diameter of the first stage vortex.
 19. An apparatus as defined in claim 17, wherein the primary fuel is viscous at ambient supply temperature, the apparatus further comprising a primary fuel supply system to provide the primary viscous fuel for combustion, the primary fuel supply system including: a compressed gas injector connected to a portion of the primary fuel supply system to form at least a suspension to thereby minimize a size of fuel droplets exiting the at least one primary fuel nozzle; a temperature sensor positioned to detect an exhaust gas temperature of the exhaust gas exiting the combustion exhaust conduit; and a logic circuit configured to control a flow of the igniter fuel into the precombustion chamber responsive to the exhaust gas temperature of the exhaust gas exiting the combustion exhaust conduit.
 20. An apparatus as defined in claim 17, wherein the pre-combustion chamber housing has an axial length to main body cross-sectional diameter ratio of between 2.5:1 to 4:1; wherein the combustion air to mass flow of the primary fuel has a ratio of between 30:1 to 50:1; and wherein the combined airflow rate of the combustion air entering the precombustion chamber is set based upon predetermined ratios of momentum and mass flow of primary fuel for a given fuel flow rate defining an air-fuel flow to thereby enhance instability of the air-fuel flow.
 21. A method of providing flameless combustion of a viscous fuel, the method comprising the steps of: inducing a first stage vortex in a primary fuel-air mixture within a main body portion of a precombustion chamber of a flameless combustor; receiving the primary fuel-air mixture having the first stage vortex induced state within a main body of a main combustion chamber of the flameless combustor; and inducing a second stage vortex in the received primary fuel-air mixture to form a complex vortex pattern to thereby enhance flameless oxidation of the primary fuel within the main body of the main combustion chamber, a diameter of the first stage vortex being substantially smaller than a diameter of the second stage vortex.
 22. A method as defined in claim 21, wherein the step of inducing a second stage vortex includes expelling the primary fuel-air mixture tangentially into the main combustion chamber cavity through a precombustion chamber exhaust outlet; and wherein the precombustion chamber exhaust outlet is axially spaced apart from the combustion exhaust conduit inlet a preselected value preselected to provide a sufficient pyrolyzed fuel travel distance from the precombustion chamber exhaust outlet within the main combustion chamber cavity based upon one or more fuel performance characteristics of the primary fuel to provide substantially complete pyrolization thereof.
 23. A method as defined in claim 22, wherein the primary fuel is a glycerol fuel, the method further comprising the step of: preselecting the value of the axial separation between the precombustion chamber exhaust outlet and the combustion exhaust conduit inlet to provide the sufficient pyrolyzed fuel travel distance from the exhaust-inlet port within the main combustion chamber cavity responsive to one or more fuel performance characteristics of the glycerol fuel.
 24. A method as defined in claim 21, further comprising the steps of: interfacing a precombustion chamber with the main combustion chamber, the precombustion chamber adapted to heat and at least partially combust the primary fuel; igniting a secondary fuel within the precombustion chamber adjacent a flowpath of the primary fuel to at least partially combust the primary fuel within the precombustion chamber of the flameless combustor; sensing a temperature of the exhaust gas exiting the combustion exhaust conduit of the main combustion chamber; and controlling a flow of the secondary fuel into the precombustion chamber responsive to the exhaust gas temperature of the exhaust gas exiting the combustion exhaust conduit.
 25. A method as defined in claim 21, further comprising the steps of: interfacing a precombustion chamber with the main combustion chamber, the precombustion chamber adapted to heat and at least partially combust the primary fuel; and aerating the primary fuel prior to entry into the precombustion chamber to minimize a size of fuel droplets entering the precombustion chamber.
 26. A method as defined in claim 21, further comprising the steps of: providing a main vortex combustion chamber of a flameless combustor having a main body substantially enclosing a main combustion chamber cavity, the main combustion chamber cavity having an axial length approximately equal to or greater than an inner diameter of the main combustion chamber cavity; and providing a combustion exhaust conduit within and axially coincident with the main combustion chamber cavity, the combustion exhaust conduit having an inlet positioned at a location between an axial position distally forward of an axial midpoint position of the elongate main body of the main combustion chamber housing and an axial position within the main combustion chamber cavity adjacent the distal end portion of the main combustion chamber housing, an axial spacing of the distal end portion of the combustion exhaust conduit from an inner surface of the distal end portion of the main combustion chamber housing having a value approximately equal to or greater than that of the inner diameter of the distal end portion of the exhaust conduit.
 27. A method of providing flameless combustion of a viscous fuel, the method comprising the steps of: providing a main vortex combustion chamber of a flameless combustor having a main body substantially enclosing a main combustion chamber cavity, the main combustion chamber cavity having an axial length approximately equal to or greater than an inner diameter of the main combustion chamber cavity; and inducing flameless oxidation of a primary fuel within the main combustion chamber cavity, the step of inducing flameless oxidation comprising the step of inducing a vortex within the main combustion chamber cavity to enhance formation of a fuel air mixture.
 28. A method as defined in claim 27, wherein the main body (101) is an elongate main body (101), the method further comprising the step of providing a combustion exhaust conduit within and axially coincident with the main combustion chamber cavity, the combustion exhaust conduit having an inlet positioned at a location between an axial position distally forward of an axial midpoint position of the main body of the main combustion chamber housing and an axial position within the main combustion chamber cavity adjacent the distal end portion of the main combustion chamber housing, an axial spacing of the distal end portion of the combustion exhaust conduit from an inner surface of the distal end portion of the main combustion chamber housing having a value approximately equal to or greater than that of the inner diameter of distal end portion of the exhaust conduit.
 29. A method as defined in claim 27, further comprising the step of: injecting the primary fuel into the main combustion chamber cavity through a precombustion chamber exhaust outlet, the precombustion chamber exhaust outlet axially spaced apart from the combustion exhaust conduit inlet a preselected value preselected to provide a sufficient pyrolyzed fuel travel distance from the precombustion chamber exhaust outlet within the main combustion chamber cavity based upon one or more fuel performance characteristics of the primary fuel to provide substantially complete pyrolization thereof.
 30. A method as defined in claim 29, wherein the primary fuel is a glycerol fuel, the method further comprising the step of: preselecting the value of the axial separation between the precombustion chamber exhaust outlet and the combustion exhaust conduit inlet to provide the sufficient pyrolyzed fuel travel distance from the precombustion chamber exhaust outlet within the main combustion chamber cavity responsive to one or more fuel performance characteristics of the glycerol fuel.
 31. A method as defined in claim 27, further comprising the steps of: interfacing a precombustion chamber with the main combustion chamber, the precombustion chamber adapted to heat and at least partially combust the primary fuel; igniting a secondary fuel within the precombustion chamber adjacent a flowpath of the primary fuel to at least partially combust the primary fuel within the precombustion chamber of the flameless combustor; sensing a temperature of the exhaust gas exiting the combustion exhaust conduit of the main combustion chamber; and controlling a flow of the igniter fuel into the precombustion chamber responsive to the exhaust gas temperature of the exhaust gas exiting the combustion exhaust conduit.
 32. A method as defined in claim 31, wherein the induced vortex in the main combustion chamber is the second stage vortex, the method further comprising the step of: inducing a first stage vortex in a precombustion chamber of a flameless combustor to form a complex vortex pattern, a diameter of the first stage vortex being substantially smaller than a diameter of the second stage vortex.
 33. A method as defined in claim 27, further comprising the steps of: interfacing a precombustion chamber with the main combustion chamber, the precombustion chamber adapted to heat and at least partially combust the primary fuel; and aerating the primary fuel prior to entry into the precombustion chamber to minimize a size of fuel droplets entering the precombustion chamber.
 34. A method as defined in claim 28, further comprising the step of: selecting a shape of the main body of the main combustion chamber that provides a substantially uniform temperature and pressure distribution inside at least a substantial portion of the main chamber and that substantially optimizes a pressure drop adjacent the inlet of the combustion exhaust conduit. 